ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Solution properties of iron(III) complexes with 5-fluorosalicylic acid — spectra, speciation, and redox stability
Rastislav Šípoš, Jozef Šima, Pavol Tarapčík, and Béla Gyurcsik
Department of Inorganic Chemistry, Slovak University of Technology, 812 37 Bratislava, Slovakia
Received: 18 December 2007 Revised: 26 February 2008 Accepted: 18 March 2008
Abstract: Iron(III)-5-fluorosalicylic acid systems were investigated in water by pH potentiometry combined with UV-VIS spectrophotometry.
The data revealed that stable aquated mono-, bis-, and tris(5-fluorosalicylato) iron(III) complexes are formed together with
their monohydroxo and dihydroxo analogues. The stability constants of all present iron(III) species were calculated. Based
on pH and the metal: ligand ratio dependent distribution of the species, electronic absorption spectra of the complexes in
the visible region were obtained. Redox stability was monitored as an ability to undergo both spontaneous and photoinduced
reduction of iron(III) to iron(II). Complexes do not undergo any redox changes when in dark neither in methanol nor in water.
While aqueous solutions of complexes are stable under the influence of incident visible radiation, steady-state irradiation
of the methanolic systems by visible light led to photoreduction of iron(III) to iron(II), the quantum yield of iron(II) photoformation
Keywords: iron(III) complexes - 5-fluorosalicylic acid - spectra - speciation - photoredox chemistry
Full paper is available at www.springerlink.com.
Chemical Papers 62 (5) 496–503 (2008)